1. Field of the Invention
The present invention relates to an optical disk recording/reproducing apparatus for recording or reproducing information on or from an optical disk, and more particularly, to a tracking control of an optical pickup over an optical disk.
2. Description of the Related Art
Conventionally, an optical disk recording/reproducing apparatus performs a tracking control of an optical pickup over tracks of an optical disk, employing a tracking error signal acquired from the optical disk, when driving the optical disk during a recording or reproducing process.
As conventional arts for such tracking control, an information reproducing apparatus is described in JP-A-7-153210, and a tracking control device is described in JP-A-11-007639. In the information reproducing apparatus as described in JP-A-7-153210, a microcomputer takes in a DC voltage corresponding to a PWM output to control an outgoing beam of an optical pickup via an A/D converter, measures a conversion error of the A/D converter, corrects a converted value from the A/D converter with the conversion error, and adjusts a tracking error signal based on this correction value, before adjusting the balance position of a tracking error signal acquired from the optical disk.
The tracking control device as described in JP-A-11-007639 configures the driving parameters according to a type of the optical disk, turns off a tracking servo and excites an output beam of an optical pickup in a radial direction of the optical disk, integrates the tracking error signal by multiple times within a predetermined period of time and in a predetermined area to calculate a mean value, controls that the mean value settles within a predetermined range, and then turns on the tracking servo.
However, with the conventional arts as described above, the tracking control of the optical pickup over the optical disk is made so that the balance position of tracking error signal is aligned in a precise center of a pit on the track of the optical disk. Therefore, when a pit on the track of the optical disk is asymmetrical with respect to the center, there occurs a problem that a reproducing signal from the optical disk is degraded in precision, if the tracking control is made by aligning the balance position of tracking error signal in the center.
That is, with those conventional arts, there occurs a problem that a precision of the reproducing signal is difficult to enhance, when the pit on the track of the optical disk is asymmetrical with respect to the center. The reason that the pit on the track of the optical disk is asymmetrical with respect to the center is that the pit is formed asymmetrically with respect to the center in recording due to characteristics or properties of the optical disk recording/reproducing apparatus.